Firing head



March 10, 1959 Filed Jan. 1l. 1954 T.L. LONG FIRING HEAD 2 Sheets-Sheet1 AT1-0R Hevs T. L. LONG A March .10,` 1.959

FIRING HEAD 2 Sheets-Sheet 2 Filed Jan. 11. 1954l INVENTOR. 'Tx-owns L.LON@ BY www,

United States Patent FIRING HEAD Thomas L. Long, Houston, Tex., assignorto Johnston This invention relates to the perforating of well casings inoil wells, and particularly to a tiring head for discharging theperforating elements of a perforating gun.

It is among the objects of the present invention to provide a simple anddependable mechanism for discharging the perforating elements carried bya perforating gun when the gun has been lowered to a desired depth in awell.

Another object is to provide a tiring head constructed as a unit whichis readily connectable between a string of pipe and a perforating gunlowered thereby'into a well casing, and operable by means of a go-devilintroduced into the string of pipe from the top of the well.

Another object is to provide a firing head in which detonating means iseffectively sealed into a tiring head provided with a tiring pinnormally held in a cocked position, and releasable to permit itsactuation by hydraulic pressure to detonate a firing charge.

A further object of the invention is to provide improved structuredevised to facilitate the assembly and operation of the device, and toincrease the etiiciency and dependability of the device for its intendedpurposes.

The invention has other objects and features of advantage, some of whichwith the foregoing will be explained in the following description ofthose forms of the invention illustrated in the drawings. It is to beunderstood that the invention is not limited to the embodiments shown inthe drawings as the inventive idea may be otherwise embodied within thedefinition of the claims.

In the drawings:

Fig. 1 is a broken vertical mid-sectional view of a firing headembodying the principles of the present invention, the parts being shownin detonating position.

Fig. 2 is a view similar to Fig. 1 illustrating the mechanism with thefiring pin held in its normal cocked position, in readiness for release.

Fig. 3 is a transverse sectional view, the plane of the section beingindicated by the line 3-3 of Fig. 2.

Figs. 4 and 5 are views partly in elevation, and partly in verticalmid-section, showing a modified form of the pin holding and releasingmeans, the firing pin being shown in its detonating position in Fig. 4and in its cocked position in Fig. 5.

Fig. 6 is a transverse sectional view, the plane of the section beingindicated by the line 6*-6 of Fig. 5.

In terms of broad inclusion, the tiring head of the present inventioncomprises a body connectable between a string of pipe and aperforating'gun and provided with axially spaced tiring and controlchambers connected by an axial bore. A firing pin is slidably movablewithin the bore between a cocked position and a detonating position theends of the tiring pin being disposed within the tiring and controlchambers, and being normally held in cocked position by spring actuatedmeans releasable by a go-devil to permit operation of the tiring pins byhydrostatic pressure. Preferably the device comprises a pair otthreadedly connected'sections enclosing a firing 2,876,701 Patented Mar.10, 19159 charge and a tiring pin assembled as a unit for connectionbetween a string of pipe and a perforating gun.

In terms of greater detail, the tiring head of the present inventioncomprises upper and lower body sections 1 and 2 threadedly joined bymeans of a threaded ex tension 3 formed on the lower end of the bodysection 1 engaging a correspondingly threaded recess in the upper end ofbody section 2. The upper end of the body section 1 is internallythreaded, as at 4, for engagement with the lower end of a string of pipedesignated 'in gen eral by the numeral 5. The lower body section 2 isprovided With a reduced extension 6 externally threaded as at 7 forengagement with a perforating gun, not shown, directly or through asuitable sub.

The engaging ends of the sections 1 and Z are recessed to form a liringchamber within which is tted a tiringblock 8 having bores 9 arranged toreceive detonating shells 10. An axially disposed bore 11 formed in thelower section 2 communicates between the tiring chamber and a threadedrecess 12 formed in the extreme' 10 for exploding the booster cap 14.Suitable sealingV means 16, such as an O-ring, is engaged between themeeting ends of the sections 1 and 2. Similar sealing means 17 isengaged between the coupling member 13 and the lower end of the section2. The O-rings 16 and 17 seal in the detonating shells, the powder trainand the booster cap included therein, for igniting the primacord 15.

The body section 1 is provided with a control chamber 20 communicatingwith the string of pipe 5 threaded into the upper end of the bodysection. The control chamber communicates with the ring chamber througha passage 21, preferably axially disposed within the body section, andarranged to slidably engage a tiring pin 22. The lower end of the tiringpin 22 is provided with an enlarged head 23 movable within an enlargedportion 24 formed in the passage 21 immediately above its juncture withthe chamber within which the firing head 8 is seated. A shoulder 26limits upward movement of the head 23, which is movable downwardly fromits uppermost position into tiring engagement with the upper ends of thedetonating shells 10. j

Within the control chamber 20, suitable retaining means is provided forreleasably securing the tiring pin 22 in its raised or cocked positionagainst the shoulder 26. In the preferred structure illustrated in Figs.l, 2, and 3 of the drawings, this retaining means comprises a` sleeve 27slidably engaging the upper end of the firing;

pin. A control cap 28 is slidably mounted over the upper end of thesleeve 27, and is provided with a head plate: 29 secured within the topof the cap 28 to extend over the top of the sleeve Z7 and firing pin 22.

An annular groove 33 is formed upon the pin 22 near its upper end toreleasably engage retaining balls 31, which are normally seated inreceptacles 32 formed in the sleeve wall. The balls 31 are held inlocking engagement with the groove 33 by the surrounding wall portion ofthe cap 2S when the cap is in its normal raised position. Upwardmovement of the cap 28 relative to the sleeve 27 is limited by a ange34, inwardly disposed at the lower end of the cap, and engaging ashoulder 35 formed on the sleeve 27 in spaced relation to the groove 33.A compression spring 37 is mounted over the sleeve'27 between the cap 28and a retaining ilange 38 threaded or otherwise secured to the lower endof the sleeve and seating upon the bottom of the control chamber 2t). Inits uppermost position, as limited by the engagement of the flange 34with the shoulder 35, the control cap is held with the head plateimmediately below the bottom of the string of pipe 5, and in axialalignment therewith. The recess within the cap 2S and within which theupper end of the sleeve 27 is received, is enlarged at its upper end byan amount which slightly exceeds the depth of the annular groove 33.When the cap is pressed downward ly over the upper end of the sleeve,the retaining balls 31 may move radially out of engagement with thegroove, and thereby release the tiring pin.

Ports 41 are formed in the wall of the lowermost section of pipe 5, at apoint above its engagement with the upper body section 1. Also, ports 42are formed in the side walls of the cap 28. The ports 41 permit therowof well fluid into the pipe 5, and thence into the control chamber 20.The ports 42 in turn permit flow of said iiuid into the upper portion ofthe cap 28, so as to equalize the hydrostatic pressure above and belowthe cap and its head plate 29. Flow of such well iluid along the bearingarea between the tiring pin 22 and the inner surface of the passage 21is prevented by appropriate sealing means, such as one or more O-rings43.

Preferably a bore 44 is formed diametrically through the tiring pin 22at a point such that it will be aligned with a corresponding bore 45formed in the upper body section 1 when the pin is raised to its normalcocked position, as best indicated in Fig. 2 of the drawings. Thispermits a retaining pin (not shown) to be inserted through theregistering bores to lock the pin against inadvertent displacementduring shipment, storage or manipulation while the tiring head is beingconnected between a perforating gun and a string of pipe. The retainingpin is of course removed before the head is lowered into the well.

Figs. 4, and 6 illustrate a modified means for holding the firing pin 22in its cocked position. In this arrange* ment a plurality of springactuated retaining iingers 50 are mounted within the control chamber forreleasably engaging a head 51 formed upon the upper end of the firingpin 22. The head 51 is received within locking recesses 52 formed on theinner edges of the lingers 50, which are arranged to form a unit ofannular form seating within the chamber 20. The ngers are normally heldin contracted relation in engagement with the head 51 by any suitablespring means. By way of illustration, an encircling spring 53 may beused as shown in Figs. 4, 5 and 6 of the drawings. The upper ends of thefingers diverge to define a concave recess faced upwardly in alignmentwith the bottom of the pipe 5, and are arranged to be spread apart by ago-devil 54 to release the head 51 from retaining engagement by therecesses 52.

ln operation, the tiring head is assembled and loaded as a unit byinitially moving the firing pin 22 to its normal cocked position whereit is releasably held by the retaining means provided in the controlchamber 20. A locking pin may be inserted through the registering bores44 and 45, as a further guard, if desired. With the tiring pin thussecurely held in its cocked position, the firing block 8 withappropriate detonating shells 10 carried by the bores 9, is seated forengagement between the upper and lower sections 1 and 2 where it issecurely held when the sections are screwed together, as indicated inthe drawings. A powder train is introduced into the bore 11 before orafter the sections 1 and 2 are screwed together; and the coupling 13,with the booster cap 14 in place therein, is then secured to the lowerend of the assembly as indicated in the drawings.

The assembled sections 1 and 2 are connected as a unit between thestring of pipe 5 and a perforating gun, not shown, in accordance withconventional practice, after which the assembly is lowered by the stringof pipe 5 to the desired depth within a well. When the perforating i gunhas been positioned at the desired point in the well, a go-devil 54 isintroduced into the string of pipe 5 from the top of the well. Thego-devil moves downwardly through the string of pipe and strikes theretaining means with sucient force to release the firing pin.

As illustrated in Fig. 1 of the drawings, the go-devil 54 drops onto thetop of the head plate 29, which is normally supported in spaced relationto the top of the ring pin 22 and sleeve Z7, as shown in Fig. 2 of thedrawings. The head plate 29, and the control cap as a whole, is subjectto balanced hydrostatic pressure of the well uid which enters the pipe 5through the ports 41 and lls the chamber 20 and cap 28. Force deliveredby the go-devil moves the control cap 28 downwardly against theresistance of the spring 37 suciently to permit the retaining balls 31to move outwardly into the enlarged upper portion of the chamber, and todisengage the annular groove 33 of the tiring pin 22. Fluid con tainedin and around the control cap 28 enters the ysleeve 27 and forces thefiring pin 22 downwardly with sucient force to explode the detonatingshells 10. The shells 10 ignite the powder train contained in the bore11, which in turn explodes the booster cap 14 and ignites the primancord 15, The projectiles or shaped charges carried by the perforatinggun are then discharged by the primacord 15 in accordance withconventional practice, which of course varies with the particular typeand construction of perforating gun employed.

The modification illustrated in Figs. 3 and 4 of the drawings operatesin substantially the same manner, thc spring fingers 50 being spread bythe action of the godevil to release the head of the tiring pin which isthen driven downwardly by hydrostatic pressure to explode the detonatingshells 10 as above explained. y

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

A tiring head adapted to be connected between a string of pipecontaining well fluid and a well perforating gun comprising: a body; acontrol chamber formed within an upper portion of said body incommunication with a string of pipe, said upper portion havingopeningstherein to admit the pressure of the well uid; a firing chamber in alower portion of said body arranged to receive a detonable charge; saidbody having a bore connecting said chambers; a tiring pin slidablyreceived in said bore for movement by the pressure of the well uidbetween a cocked position and a detonating position; sealing meansbetween said tiring pin and said bore; an annular sleeve slidablyengaging said pin within said control chamber and having an enlargeddiametral end portion; a locking means for locking said pin to saidenlarged portion of said sleeve including an annular groove on one endof said pin, lateral openings in the enlarged end portion of said sleeveand ball members disposed in said openings; a hollow control headslidably mounted on said sleeve for limited movement axially of saidsleeve between a pin locking position and a pin releasing position, saidcontrol head having an upwardly facing surface exposed to the well tluidand arranged to be struck by a go-devil, said control head furtherhaving a recess portion sized to slidably engage said enlarged endportion of said sleeve in the pin locking position of said control headthereby urging said ball members inwardly into the annular groove ofsaid firing pin and having an enlarged recess portion with openingstherein to expose the end of said pin to the pressure of the well uidand arranged to be disposed about said enlarged end portion of saidsleeve in the pin releasing position thereby permitting said tiring pinto be released; and spring means urging said head toward its lockingposition and permitting movement of said head to a pin releasingposition in response to the weight of the go-devil.

(References on following page) 5 References Cited in the lo f thispatent 2,456,977 UNITED STATES PATENTS 1,514,743 Taylor NOV. 11, 19242,760,408 2,125,487 Church Aug. 2, 1938 5 2,307,360 Collins Ian. 5, 19432,330,265 Burt Sept. 28, 1943 350,408

6 McCullough Dec. 21, 1948 Wellington July 4, 1950 Kanady Apr. 12, 1955Taylor Aug. 28, 1956 FOREIGN PATENTS France Sept. 11, 1939

